DNA polymerase type-B family
SMART accession number:SM00486
Description: DNA polymerase alpha, delta, epsilon and zeta chain (eukaryota), DNA polymerases in archaea, DNA polymerase II in e. coli, mitochondrial DNA polymerases and and virus DNA polymerases
Interpro abstract (IPR006172):

DNA is the biological information that instructs cells how to exist in an ordered fashion: accurate replication is thus one of the most important events in the life cycle of a cell. This function is performed by DNA- directed DNA-polymerases (EC by adding nucleotide triphosphate (dNTP) residues to the 5'-end of the growing chain of DNA, using a complementary DNA chain as a template. Small RNA molecules are generally used as primers for chain elongation, although terminal proteins may also be used for the de novo synthesis of a DNA chain. Even though there are 2 different methods of priming, these are mediated by 2 very similar polymerases classes, A and B, with similar methods of chain elongation.

A number of DNA polymerases have been grouped under the designation of DNA polymerase family B. Six regions of similarity (numbered from I to VI) are found in all or a subset of the B family polymerases. The most conserved region (I) includes a conserved tetrapeptide with two aspartate residues. Its function is not yet known. However, it has been suggested [(PUBMED:2461550)] that it may be involved in binding a magnesium ion. All sequences in the B family contain a characteristic DTDS motif, and possess many functional domains, including a 5'-3' elongation domain, a 3'-5' exonuclease domain [(PUBMED:8679562)], a DNA binding domain, and binding domains for both dNTP's and pyrophosphate [(PUBMED:9757117)].

GO function:DNA-directed DNA polymerase activity (GO:0003887), nucleotide binding (GO:0000166), nucleic acid binding (GO:0003676)
Family alignment:
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There are 4657 POLBc domains in 4657 proteins in SMART's nrdb database.

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